1. Field of the Invention
The present invention relates to medicament containers and, in particular, to aerosol protection guards for medicament containers having pierceable, self-sealing tops adapted for repeatable filling of hypodermic syringes by inserting needles through the top.
2. Prior Art
A problem of growing concern among health care workers is the risk of injury and disease resulting from the handling and inadvertent contamination of, or by, aerosolized drugs, especially those having high levels of toxicity such as certain cancer chemotherapy drugs. The degree of risk to workers handling these cytotoxic drugs is dependent upon the drugs' inherent toxicity and the extent to which workers are exposed to the drugs. For some drugs the degree of toxicity from accidental dosages is not well understood or known, and the effects of slight exposure over long time periods are unpredictable. It is, therefore, advantageous to those handling these drugs to take all precautions against contamination, even in cases where the drugs have no known toxicity or are of unpredictable toxicity.
Exposure to toxic drugs can be a result of inhalation of airborne dusts from recrystalized drugs or of airborne droplets, absorption of drugs through the skin from accidental contact, and ingestion of drugs with food, beverages, and the like which have been contaminated through accidental contact with the drug.
In some treatment centers the drugs are prepared in the pharmacy by pharmacy personnel. In others, they are prepared by physicians or nurses.
Most cytotoxic drugs must be dissolved, which involves transferring a solvent from one container to another, before they are administered. Contamination can occur during either preparation or administration of the drugs by either direct contact with the drug or by inhalation. Ingestion can also occur because of the drugs contact with food or beverages in the area.
Drugs may be inadvertently released into the atmosphere by way of spraying or aerosolization, which can occur both upon (a) withdrawal of needles from drug vials or (b) during the expulsion of air from drug-filled syringes, among others.
A person may come into contact with an aerosolized drug directly or indirectly, as a result of coming into contact with particles that have come to rest on surfaces.
To avoid contact with the drug under the circumstances described above, it is recommended that these drugs be handled in biological safety cabinets, the personnel handling the drugs be clothed in protective clothing and gloves, and the preparation areas be ventilated by means of withdrawing potentially contaminated air away from personnel and from other areas.
In comparison to spilling, aerosolization is a far more serious hazard because its presence may be invisible, and undetectable without recourse to elaborate testing. The aerosol is easily transported by air currents to other areas where its presence, and consequent contamination, is not even suspected. It is, therefore, necessary to contain aerosolized medicaments in order to prevent the problem in the first place.
Among the various attempts which have been made to protect workers from coming into contact with aerosolized drugs are the use of glove boxes, laminar flow hoods, protective clothing, gloves and face shields Most recently, the use of special needle apparatuses such as, e.g., the "Minispike" (TM) manufactured by Burron Medical, Inc., have been employed to aid in equalization of pressure within medicament vials.
Patented inventions aimed at shielding the worker from aerosolized drugs by means of containment of the aerosol within a cavity are numerous. U.S. Pat. No. 4,522,277 issued Nov. 12, 1985, is typical. It includes a collapsible chamber which may be either of a bag-like balloon or a telescopically collapsible shield which attaches to the top of a conventional medicament vial. No means for automatic equalization of pressure within the cavity is indicated.
U.S. Pat. No. 4,312,349 illustrates the use of a filter for filtering gases and fluids passing through a compartment. The device, however, does not provide a way of equalizing pressure between the vial and ambient, and, in case of careless use could actually result in increased pressure within the vial.
All of the prior art devices for shielding medicament vial openings suffer from lack of an effective means for equalizing pressure in the vial between the vial and ambient. As long as any pressure differential exists, however slight, an aerosolization of drugs will occur when the needle is withdrawn from the vial.
Therefore, there is a need for a medicament vial shield which traps the aerosol molecules inside the vial and which allows for equalization of pressure between the vial interior and ambient